Introduction of Computer Networks
A network is a collection of computers which have the ability to share
and exchange information, software and hardware. Computers, servers and network
devices (routers, switches and modems) communicating with each other make up a
network.
or
A
computer network is the infrastructure that allows two or more computers
(called
hosts)
to communicate with each other.
or
A
computer network is a set of computers connected in a sequence with the ability
to
share
resources and information (data).
Computer networks are
designed for the following reasons:
Sharing Resources
Reduced Cost
Reduced time
Scalability
Reliability
Security
In 1969,
U.S. Department of Defence initiated research into joining the computers of
defence and research centers into a network. This network, which become known
as ARPANET, served as a starting point for the construction of the first and
most widely known WAN, now a days known as the internet.
Types of computer network
Local Area Network (LAN)
n Covers
a small area
n Connects
computers and workstations covering a local area like, office or home
n Advantages
of LAN:
n Improves
productivity due to faster work
n Provides
easy maintenance
n New
systems can be installed and configured easily
n Disadvantages
of LAN:
n Limited
number of systems can only be connected
n Cannot
cover large area
n Network
performance degrades as number of users exceeds
Campus Area Network (CAN)
n Made
up of multiple LANs within limited area
n Connects
different LANs in a campus
Metropolitan Area Network
n Interconnects
networks within a city
n Supports data and voice transmission
Wide Area Network
n Covers
a wide geographical area which includes multiple computers or LANs e.g.
Internet
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